A lithium secondary battery pack is made by combining a plurality of unit cells into one pack and is widely used in applications requiring high energy such as a vehicle battery or an electric power storage device.
However, a battery pack including a plurality of unit cells generates heat and swells up during overcharging, and thus is deformed such that a module expands outward. In a severe case, a flame is discharged to the outside of the module. Also, a venting gas or a flame generated in a cell module may diffuse to cell modules adjacent to the cell module, thereby leading to an additional event.
In relation to technology for guaranteeing the safety of a cell module, Korean Patent Publication No. 2014-0002115 discloses a battery pack in which a gas discharging part communicating with a gas collecting part is formed in an upper cap, and Korean Patent Publication No. 2015-0065964 discloses a battery module and a battery pack having one pair of cases having gas discharging holes formed in side surfaces at positions corresponding to electrode tabs of pouch cells.
Korean Patent Publication No. 2014-0002115 discloses a battery pack including: a plurality of stacked battery modules received in a battery pack case, including: a first electrode assembly and a second electrode assembly having electrode tabs including an anode tab and a cathode tab formed to be extended from an anode plate and a cathode plate and sealed by a pouch so that the electrode tab is exposed to the outside; a battery case having one side opened in a height direction so that the first electrode assembly and the second electrode assembly are received therein; a connection mold inserted between the electrode tabs of the first electrode assembly and the second electrode assembly and the pouch to thereby connect a plurality of terminals formed on one side to the electrode tabs, and including a gas collection part formed so as to be penetrated in a height direction; and an upper cap coupled to the connection mold at the opened side of the battery case and having a gas discharging part formed therein communicating with the gas collection part; and a gas guide pipe formed to be extended in a length direction so as to be communicated with the gas discharging part of the battery module.
Korean Patent Publication No. 2015-0065964 discloses a battery module including a pouch cell in which an electrode tab is formed at one side or both sides of an electrode body; one pair of case each coupled to surround an outer surface of the pouch cell and comprising a receiving part in which the electrode body of the pouch cell is inserted and received, an opening part through which the receiving part is exposed, a terminal groove through which an electrode terminal coupled to the electrode tab of the pouch cell is withdrawn to the outside, and a gas discharging hole formed in a side surface at a position corresponding to the electrode tab of the pouch cell; one pair of heat dissipation plates respectively coupled to outer surfaces of the one pair of cases and surrounding the opening parts; and an insulating sheet located between the electrode body of the pouch cell and the heat dissipation plates.
However, in a related art battery pack or a related art battery module having a structure in which a cell module array 10 including a plurality of cell modules 10a through 10c in a predetermined pack structure 30 contacts a heat sink 20 as shown in FIG. 1, when an event occurs due to overcharging of a cell module (e.g., the cell module 10a), a venting gas or a flame may diffuse and an additional event may occur. Conventional patent documents have not disclosed technology for solving these problems, and thus there is a demand for the technology.